onClick priority over addEventListener in javascript?

BlueElixir picture BlueElixir · Apr 28, 2015 · Viewed 10.9k times · Source

Right now, I have an event listener that listens to a click on the screen. There is also a button on the screen. When I click on the button the event listener will execute before the onclick. Is there a way I can make onclick have higher priority?

<script>
document.body.addEventListener('click',function(){alert('1');}, false);

function clicked() { 
    alert('2');
}
</script>
<button onclick="clicked()">Click this</button>

Clicking the button also triggers the event handler. 1 shows before 2, when I click the button. I want 2 to show first.

Answer

musically_ut picture musically_ut · Apr 28, 2015

addEventListner's third argument is the useCapture flag. If you set it to true, handler will be executed while the event is traveling down to the button element. However, if you set it to false, the handler will be triggered while the event is bubbling up:

  capture phase  | |  / \ bubbling up
-----------------| |--| |-----------------
| element1       | |  | |                |
|   -------------| |--| |-----------     |
|   |element2    \ /  | |          |     |
|   --------------------------------     |
|        W3C event model                 |
------------------------------------------

From: http://www.quirksmode.org/js/events_order.html#link4

In your example, the onclick should be executed before the click handler on the body tag. If you want to reverse the order of execution, you should capture the event at body.